A study of the migration and stability of titania on a model Rh catalyst

Abstract

We have examined growth and stability of titania overlayers which have been vapor deposited onto a Rh foil. Titania was found to grow layer by layer, with approximately 1 × 1015 TiOx. species/cm2 in the first layer. Submonolayer coverages of titania were unaffected by heating the sample to temperatures as high as 1320 K. However, heating multilayer coverages to 1320 K resulted in one monolayer remaining on the surface, with the rest migrating into the Rh. The migrating titania could be brought back to the surface by removing the top monolayer and heating the sample above 900 K under vacuum. Saturation coverages of CO were found to decrease linearly with surface titania coverage, independent of sample treatment; however, annealing to high temperatures appears to remove defects in the titania overlayer.